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Mr. Craig. They are more numerous on and generally select orchard trees, but 

 even pine trees have been attacked by them and in some cases the branches stripped. 

 Maple trees are also attacked. 



Professor Shaler. I have seen them on some maple trees and heard ot others, but 

 it seems to be a case of starvation when they come to that. 



Mr. Craig. My observation is that the older the tree the more they will attack it. 



Professor Fernald. With regard to a scientific man on the commission, if you can 

 get an entomologist who is also a business man you w'ill be fortunate, but in my 

 judgment it is important to have a business man, too. 



To go back to the question of territory, I agree with Professor Riley that it is rather 

 stupendous, but if you can destroy the insects over a small area, why can not you 

 over a large one ? The whole thing is experimental ; it is unprecedented to destroy 

 80 large a body of insects over so large a territory, but my impression is that they can 

 be destroyed. The question is, how to do it. I was informed last summer that Paris 

 green destroyed the larvse of this insect up to a certain size ; beyond that size they 

 were able to eat it and grow fat. I urged the commission to try a branch with cat- 

 erpillars that had not eaten any Paris green, but I can not learn that they did it. If 

 their statements are correct, I must lose the little faith I had in regard to the efficacy 

 of Paris green. My experiments at Amherst on the use of Paris green do not seem to 

 tally with the results they got out of it. They used 1 x^ouud of Paris green to 150 gal- 

 lons water, and when Mr. Sessions and I went over there in the summer we saw that 

 the trees were burned very little. The same proportions used at Amherst burned the 

 trees very badly. Yet Professor Cook and others have reported that a much larger 

 proportion of Paris green could be used. The Paris green I used I had analyzed, and 

 know just what it was. I expect there is either some great difference between the 

 climate of Amherst and this region or — something else. 



Mr. Craig. So far as my own orchard is concerned, where the Paris green was used 

 a streak was burned here and there ; in other places not. I think it was not kept 

 stirred up. 



Professor Fernald. Suppose it is not possible to destroy the insect ? Even then 

 I believe it would pay to make annual appropriations to hold them in check. We 

 know what the farmers are paying annually to destroy the potato beetle, and if this 

 insect spreads over the Commonwealth of Massachusetts I should suppose it was 

 capable of doing more damage than the Potato Beetle. It seems to me if it is not 

 possible to stamp it out it is wise to hold it in check where it is. 



Mr. Sessions. I have heard the idea advanced by somebody from Medford that 

 possibly the reason the caterpillars apparently eat Paris green and live, is that after 

 a certain stage of their existence they stop eating altogether. 



Professor Fernald. They do not stop eating long before they spin their cocoons. 

 The time is not more than 24 hours. 



Professor Shaler. I should like to ask about the chances for more satisfactory in- 

 secticides. I should like to ask if we may reckon among the insecticides certain com- 

 pound salts of calcium which are very acrid, and whether a solution of them would 

 be efficacious ? 



Professor Fernald. I have had no experience with them. 



Professor Shaler. The question is whether it would serve in this case. Do you 

 know, Professor Riley ? 



Professor Riley. I should have most faith in the arsenicals. The relative value of 

 the different forms of arsenic spraying depends partly upon the kind of tree treated, 

 partly upon the condition of the atmosphere, and very materially upon the purity 

 of the material. Paris green has this advantage, that it may be used much more 

 strongly, with less injury to the tree ; and it has this disadvantage as compared with 

 London purple or pure arsenic, that it is not soluble in water, and you have to keep 

 stirring it. I have no doubt that the experience Professor Fernald referred to was 

 due to the inferior character of the Paris green in the one case and its purity in the 

 other. It should be applied with a spraying nozzle that would simply touch it to 



